修复: 安全 8 项 + create_project 自动建目录

- ① relay token 必设环境变量 DF_RELAY_TOKEN,移除硬编码默认
- ② AiProviderRecord Debug 脱敏 api_key/model_configs/config
- ③ ScriptNode 危险命令告警(rm -rf/DROP TABLE/Format 等)
- ④ bind_directory 路径规范化,拒绝含 .. 的原始路径
- ⑤ StateMachine 文档警告不得在 await 期间持锁
- ⑥ EventBus send 错误改 tracing::warn 不再静默吞噬
- ⑦ probe_pwsh OnceLock 全局缓存,异步探测不阻塞 tokio
- ⑧ retry jitter 改 rand crate,范围扩大到 ±50%
- create_project 目录不存在时自动创建,消除死锁链

crates/df-ai/Cargo.toml

@@ -17,3 +17,4 @@ tracing = { workspace = true }
 reqwest = { version = "0.12", features = ["stream", "json"] }
 futures = "0.3"
 eventsource-stream = "0.2"
+rand = "0.8"